Answer this question truthfully
### Question: What causes Allergic conjunctivitis?
### Response: When your eyes are exposed to anything to which you are allergic, histamine is released and the blood vessels in the conjunctiva become swollen. Reddening of the eyes develops quickly, along with itching and tearing.
The pollens that cause symptoms vary from person to person and from area to area. Tiny, hard-to-see pollens that may cause hay fever include:
Grasses Ragweed Trees The amount of pollen in the air can affect whether you develop symptoms. There is more likely to be increased amounts of pollen in the air on hot, dry, windy days. On cool, damp, rainy days most pollen is washed to the ground.
Allergies tend to run in families, although they are not inherited in any obvious way. It is hard to know exactly how many people have allergies, because many different conditions are often lumped under the term allergy.